Battery or Alternator

[DavePS]

So, My 2013 CX-9 out of warranty for 6 months now, would not start last night. A quick jumper cable connection and it started in a jiffy and was good to go in 2 minutes.

I drove home for about 15 mins. This morning when I tried it started up OK. Now at work in my other car.

So, here I am trying to evaluate the situations so that I do not get with a dead car at an unforseen location/timing. The only thing that I noticed was that it was a little slow cranking to start the 3 other times I started the car yesterday. Everything was fine with the car about a week ago when I last used it. It is my family car, I drive another for work on a daily basis.

Now, how do I know if it is a failing battery, failing alternator, a one-off-accidental battery drain or something more diabolic. I will test and watch the car a bit more to see if things just fix themselves, but am curious for feedback, guidance and help.

Thanks.
DavePS

 

[mazdadude]

Check the water level of the battery. (How old is the battery?)

Test voltage, and load test the battery.

Test Alternator output.

Most likely (especially if it is the original battery), the water level has now been depleted to the point where it can no longer handle the 1 week of discharging you are demanding from it between charges. If you are handy and frugal, some batteries can be saved by properly topping off with distilled water.

 

[rsvinylgraphics]

If it still has the original battery, that is most likely the issue here, batteries seem to last only about 3-5 years nowadays.

If you have a multimeter you can check your alternator voltage output, you should be getting around 14.3 volts at the battery posts with the engine running.

 

[paris1]

If it's the original battery, forget all the testing suggested here and just go go Costco and pony up $75 for a new battery.Yours is 5 years old and the odds are 99.7% that that's the problem. It was last month on my 2013 CX-5!

 

[danmm7]

I agree that this is likely the battery. To be 100% sure, Any car parts store should be able to test your existing battery and diagnose the charging system for FREE.

Or, simply save yourself some time and just get a new battery. Get a good quality one, not the cheapest brand/model you can find. Cheap batteries may last only 1-2 years. The quality has been going downhill progressively.
I also had a Costco bought Interstate battery that died on me on the 5th month!!! It was not holding charge more than a day. I returned it, got a new one, Interstate again.... and so far, it's been good for the last 19 months.

At this age, your original battery is likely dying. I would not attempt to service it (add water, etc) since most modern batteries are NOT serviceable at home. You're playing with acid. Don't do it, unless you know very well what you're doing.

 

[DavePS]

Thank you all so much. I will get a new battery and have them test stuff at that time just to be sure.

 

[Srad600]

If you rarely use the car, get a trickle charger. It'll save you from some battery issues down the line. It won't do anything if you have a bad alternator though, so you should still get both the battery and alternator tested.
I have motorcycles that sit for long periods between uses and a good trickle charger is a lifesaver.

 

[PTguy]

Are the battery cable clamps clean & tight?

Can you use a voltmeter? Measure the battery voltage with the engine off. Start the engine. Measure the voltage with the engine running. If the voltage is higher with the engine running, the charging system is good and you need a new battery. If the voltage is lower with the engine running, you need to fix the charging system.

I agree, highly likely you're gotten your money's worth from that battery.